dsh-audio-copilot: Add voice input to DeepSeek Harness chat box

dsh-audio-copilot is a DSH voice input plugin maintained by ai-yucheng, based on DSH 0.1.0-rc.7 and licensed under the MIT license. This plugin allows users to click the microphone button in the chat box to speak, automatically filling the transcribed text into the input box via multi-engine ASR. It supports four engines: zhipu, local, gemini, and openai. zhipu excels at Chinese dialects and foreign languages and operates on a pay-as-you-go basis; local uses faster-whisper for offline transcription and requires downloading a model of approximately 460MB to 1.5GB; gemini's free tier includes rate limiting and an automatic retry mechanism; and openai is available as an optional engine. Prerequisites include DSH Desktop, Node.js ≥ 20, and the PATH environment variable.